Tag: quantitative chemistry

Questions Related to quantitative chemistry

Which statement is linked with the idea that two identical containers filled with different gases will contain the same number of particles?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. Mosely

  2. Avagadro

  3. Dalton

  4. Mendeleev

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Correct Option: B
Explanation:

Avagadro stated that when two identical containers are filled with different gases at same pressure and temperature, they contain same number of particles.

So, the statement is linked with Avagadro.

What is the volume occupied by 17.75 g of $Cl _2$ at STP?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. $5.6l$

  2. $22.4l$

  3. $11.2l$

  4. $2.8l$

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Correct Option: A
Explanation:

In order to solve this problem, we would use the ideal gas law formula PV = nRT 

at STP standard temp and pressure is 1 atm and 273k

we have 

P = 1atm, n = $\dfrac{17.75}{70.90}$ mole = 0.250, R = $0.0821$ $atm*L/mol*K$ , T=$273K$

V = $\dfrac {nRT}{P}$

= $0.250\times 0.0821\times 273$

= $5.6L$

answer is A


Which term describes the mass of $6.022\times { 10 }^{ 23 }$ representative particles?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. Molar mass

  2. Avogadro's number

  3. Empirical formula

  4. Molecular formula

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Correct Option: A
Explanation:

Molar mass of a compound describes the total mass of $6.023 \times 10^{23}$ atoms or particles of the compound.

Ex: Molar mass of $H _2 = 2\space g$

A sample of ammonia has a mass of $51.1g$. How many molecules are in this sample?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. $1.8\times {10}^{23}$ molecules

  2. $3.6\times {10}^{23}$ molecules

  3. $9.1\times {10}^{23}$ molecules

  4. $1.8\times {10}^{24}$ molecules

Show answer
Correct Option: D
Explanation:
given mass of ammonia is 51.1g
in this number of moles =  $\dfrac{51.1}{17.031}$ = 18
Now in a mole, there are Na molecules, this is known $6.023\times 10^{23}$ 
since 1 mol = $6.023\times 10^{23}$ 

thus,

18 mol = $18\times 6.023\times 10^{23}$  = $1.8\times 10^{24}$

How many moles are present in $6.023\times 10^{22}$ molecules of $CO _2$?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. 0.2

  2. 0.01

  3. 0.1

  4. 0.02

Show answer
Correct Option: C
Explanation:

1 mole of $CO _2$ contains 1 $N _A$ molecules. ( $N _A=6.023\times10^{23}$)

Moles present in given sample are: $6.023\times10^{22}\div N _A=0.1$

Two gases A and B are taken in same volume containers under similar conditions of temperature and pressure. In container A, there are '2N' molecules of gas A. How many number molecules does container B have? 

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. 2N

  2. 4N

  3. N

  4. 8N

Show answer
Correct Option: A
Explanation:

Avogadro's law: Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

Thus ans is 2N.

Assertion : 20 gm of argon (atomic mass of Ar $=40)$ occupies volume of $22400\ cm^3$ at STP.
Reason : 20 gm of Neon (atomic mass of $Ne=20$) occupies a volume of $22400\ cm^3$ at STP.

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

  2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

  3. Assertion is correct but Reason is incorrect.

  4. Assertion is incorrect but Reason is correct.

  5. Both assertion and reason are incorrect.

Show answer
Correct Option: D
Explanation:

20 g of argon is 0.5 moles and it occupies $(0.5\times 22400=)11200\ cm^3$ at STP.
20 g of Neon is 1 mole and occupies a volume of $22400\ cm^3$ at STP.

According to Avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain:

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. the same number of molecules

  2. different number of molecules

  3. the same number of molecules only if their molecular masses are equal

  4. the same number of molecules if their densities are equal.

Show answer
Correct Option: A
Explanation:

According to avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain, the same no. of molecules.

For eg. One volume of hydrogen combines with one volume of chlorine to produce two volumes of HCl gas.
$H _2\1vol$   $+$  $Cl _2=\1 vol$ $2HCl\2 vol$

Which of the following statements is the most accurate with regard to the significance of Avogadro's number, $6.02 \times 10^{23}$ ?

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. It is the conversion factor between grams and atomic mass units.

  2. It is a universal physical constant just as the speed of light.

  3. It is the number of particles that is required to fill a $1\ L$ container.

  4. It is the inverse diameter of an $H$ atom .

Show answer
Correct Option: A
Explanation:

A carbon atom weighs 12 AMU, one AMU is equivalent to $1.66 \times 10^{-24}$ grams. Conversely, one gram is equivalent to $6.022 \times 10^{23}$ AMU, which is called Avogadro's number


so the answer is A

The volume occupied by half a mole of a gas at STP is:

chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

  1. 5.6 L

  2. 11.2 L

  3. 22.4 L

  4. 44.8 L

Show answer
Correct Option: B
Explanation:
The volume occupied by 1 mole of any gas is 22.4 litres.

So the volume occupied by half a mole of gas would be half of 22.4 litres.

So it will be $11.2\ litres$.

Hence, option B is correct.